Topic: 250 XS Problem/Question?

This topic has 5 replies, 4 voices, and was last updated 14 years, 8 months ago by Waterboy.

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October 4, 2011 at 12:26 pm #412071

Waterboy
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I noticed at the lake this wekend that my motor was running a little rough at idle speed. It also has lost about 400 rpms at WOT. Back in May I was turning 6000 RPMs and running about 77-78mph. This weekend it is turning 5600 RPMs and only running 72mph. The air temp is cooler and the loads are the same. I have heard several people talk about bad coils on the Mercs. So you guys think this is my problem. It is under warranty, so I am going to take it to the shop, just wondered what it may be. Spinning a 26 Fury.

October 4, 2011 at 1:14 pm #412072

Bass Cat Boats
Keymaster

Fuel is a possibility too, though take it in and have it checked out.

October 4, 2011 at 1:17 pm #412076

Waterboy
Participant

I always run 89 Octane and Quickleen. The fuel never stays in the tank for over a month.

October 4, 2011 at 2:50 pm #412079

pops77s
Participant

I would go back to the lower 87 octane, it will run better in a lower compression (stock) engine and is cheaper. The higher the octane, the cooler the burn (less power). It is designed for higher compression engines to eliminate pre detonation in the combustion chamber (spark nock).BrianBrianHAWG Hunter2013 BassCat Eyra2013 Mercury 250 Pro XS Gen2 L/U

October 5, 2011 at 3:48 am #412082

dropshot85
Participant

I have a 2007 250 ProXS, and had similar problems earlier in the year, except to a higher degree. It was bogging down as I tried to get on plane, running rough and would only top out at 4500-5000 rpm. Blown coil was the culprit. Thankfully still under warranty. When I took it into my mechanic, he told me that Merc wanted to replace all 6 coils, which was fine with me. Id make sure they do the same thing with yours. PS – I cant tell you what a difference a competent mechanic will make. He was able to diagnose the problem after a 3 minute phone conversation. If youre anywhere near Chicago, I have the guy for you. Hes worth the drive.

October 5, 2011 at 10:52 pm #412084

Waterboy
Participant

Im in SC, but thanks for the help.
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